//C09:9.8:binary.c
#include <stdio.h>

void to_binary(unsigned long n);
int main(void)
{
	unsigned long number;
	printf("Enter an integer (q to quit):\n");
	while (scanf("%ul", &number) == 1)
	{
		printf("Binary equivalent: ");
		to_binary(number);
		putchar('\n');
		printf("Enter an integer (q to quit):\n");
	}
	printf("Done.\n");
}

void to_binary(unsigned long n)
{
	int r;
	r = n % 2;
	if(n >= 2)
	{
		to_binary(n / 2);
	}
	putchar('0' + r);
	return;
}
